[GHC] #12844: No Skolem Info with PartialTypeSignatures
GHC
ghc-devs at haskell.org
Fri Dec 2 16:03:43 UTC 2016
#12844: No Skolem Info with PartialTypeSignatures
-------------------------------------+-------------------------------------
Reporter: crockeea | Owner:
Type: bug | Status: closed
Priority: normal | Milestone: 8.0.2
Component: Compiler | Version: 8.0.1
Resolution: fixed | Keywords:
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: Compile-time | Test Case: partial-
crash or panic | sigs/should_compile/T12844
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
-------------------------------------+-------------------------------------
Changes (by bgamari):
* status: merge => closed
* resolution: => fixed
* milestone: => 8.0.2
@@ -3,1 +3,1 @@
- {{{
+ {{{#!hs
New description:
The following program triggers a panic:
{{{#!hs
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE PartialTypeSignatures #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
barWraper :: ('(r,r') ~ Head rngs, Foo rngs) => FooData rngs
barWraper = bar
bar :: (_) => FooData rngs
bar = foo
data FooData rngs
class Foo xs where foo :: (Head xs ~ '(r,r')) => FooData xs
type family Head (xs :: [k]) where Head (x ': xs) = x
}}}
{{{
> ghci NoSkolem.hs
[1 of 1] Compiling Main ( NoSkolem.hs, NoSkolem.o )
NoSkolem.hs:8:13: error:ghc: panic! (the 'impossible' happened)
(GHC version 8.0.1 for x86_64-unknown-linux):
No skolem info: k_aYV[sk]
}}}
I haven't tested with 8.0.2 or head.
--
Comment:
Merged to `ghc-8.0` as 4212674ba92971734eec064809f8e1a45bca992a.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12844#comment:3>
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